Using panel data, the fixed effect regression specification is given by
$y_{it} = a_i + \beta' x_{it} + \epsilon_{it}$
where $a_i$ are the fixed effects.
The fixed effects estimator $\beta_{FE}$ eliminates the fixed effects by time-demeaning, i.e.
$\bar{y_i} = \hat{\beta'}_{FE} \bar{x_i} $
where $\bar{y_i} = \sum_{t=1}^T y_{it}/T$ and similarly for $\bar{x_i}$.
The fixed effects can then be recovered by $\hat{\alpha_i} = \bar{y_i} - \hat{\beta'}_{FE} \bar{x_i}$.
My question: How do I get the standard errors for the fixed effects $\hat{\alpha_i}$ without using the least squares dummy variable (LSDV) estimator?